A large Legionnaires outbreak has been linked to hot tubs at the North Carolina State Fair last month, causing at least 150 illnesses and four deaths so far.

The North Carolina Department of Health and Human Services issued a status update last week, involving reports of Legionnaires disease among individuals who attended the Western North Carolina Agricultural Center between September 6 and 15, and walked by a hot tub display inside the Davis Event Center.

As of October 14, at least 141 people are confirmed to have been diagnosed with Legionnaires’ and another eight people reportedly have a milder form of the disease, called Pontiac fever. Four people have died and 94 have been hospitalized due to the illnesses.

Investigators say the outbreak was spread by the hot tub displays and poorly maintained water systems. While samples taken from the hot tubs tested negative for Legionella pneumophila, the bacteria associated with the disease, the environmental samples were not collected until two to three weeks after the fair ended.

Another sample taken from the women’s restroom at the Davis Event Center tested positive for Legionella pneumophila bacteria, but the strain was genetically different from the strain collected from patients who had been sickened by the outbreak. Testing and investigations are ongoing.

Officials said the Agricultural Center’s water system was treated with a thermal eradication disinfecting process in early October as a precautionary measure.

Legionnaires disease is a serious lung infection that occurs when the Legionella bacteria spreads through water droplets in the air and are breathed in, for example from water vapor from a hot tub. The disease can be treated with antibiotics, but one in 10 people diagnosed with the disease will die.

Symptoms of Legionnaires disease include coughing, muscle aches, fever, shortness of breath and headaches. In serious cases, patient’s may need to be hospitalized.

At least one person contracted Legionnaires’ disease who did not attend the state fair. Instead, they attended a quilt show at the end of September at the same Agricultural Center. This is the only case of Legionnaires reported among someone who has not attended the North Carolina Mountain State Fair, according to the state investigators.

At least one lawsuit has been filed against All Pro Billiards & Spas and Soft Fun; who both had displays at the fair. The lawsuit was filed by an individual who was hospitalized after spending time at the Davis Center and speaking with a hot tub salesman.